There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Organic Photoredox Catalysis

介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

A flow-focusing geometry is integrated into a microfluidic device and used to study drop formation in liquid–liquid systems. A phase diagram illustrating the drop size as a function of flow rates and flow rate ratios of the two liquids includes one regime where drop size is comparable to orifice width and a second regime where drop size is dictated by the diameter of a thin “focused” thread, so drops much smaller than the orifice are formed. Both monodisperse and polydisperse emulsions can be produced.

/pdf/formation-of-dispersions-using-flow-focusing-in-2zw2hx9w2y.pdf

Formation of dispersions using “flow focusing” in microchannels

In Part 2, the factors impacting the Claisen rearrangement both in batch and flow processing are analyzed, including the choice of substituent, catalyst, temperature, pressure, concentration, flow rates, and solvent. Part 1 of this review series discussed the potential of using short-time spectroscopy and quantum mechanical calculations to elucidate the mechanism and transition state of the Claisen rearrangement. Flow processing offers profound opportunities for studying these factors known to impact the Claisen rearrangement done in batch. It is shown that the same impact factors also rule flow processing, yet now superposed by the very different residence and reaction time settings and by novel process windows which go beyond conventional processing. As a result, massive intensification can be reached and a mechanistic analysis can be done in entirely unpaved processing fields. This links to the analysis given in part 1: it is likely that flow processing can further promote the understanding of the mechanism and transition state of the Claisen rearrangement and, thereby, promote the achievement of better reaction performance.

/pdf/the-claisen-rearrangement-part-2-impact-factor-analysis-of-iu9k9s30c7.pdf

The Claisen Rearrangement – Part 2: Impact Factor Analysis of the Claisen Rearrangement, in Batch and in Flow

Nanotechnology is increasingly being utilized to create advanced materials with improved or new functional attributes. Converting fertilizers into a nanoparticle-form has been shown to improve their efficacy but the current procedures used to fabricate nanofertilisers often have poor reproducibility and flexibility. Microfluidic systems, on the other hand, have advantages over traditional nanoparticle fabrication methods in terms of energy and materials consumption, versatility, and controllability. The increased controllability can result in the formation of nanoparticles with precise and complex morphologies (e.g., tuneable sizes, low polydispersity, and multi-core structures). As a result, their functional performance can be tailored to specific applications. This paper reviews the principles, formation, and applications of nano-enabled delivery systems fabricated using microfluidic approaches for the encapsulation, protection, and release of fertilizers. Controlled release can be achieved using two main routes: (i) nutrients adsorbed on nanosupports and (ii) nutrients encapsulated inside nanostructures. We aim to highlight the opportunities for preparing a new generation of highly versatile nanofertilisers using microfluidic systems. We will explore several main characteristics of microfluidically prepared nanofertilisers, including droplet formation, shell fine-tuning, adsorbate fine-tuning, and sustained/triggered release behavior.

Microfluidic encapsulation for controlled release and its potential for nanofertilisers.

From Microreactor Design to Microreactor Process Design

Reactor Concepts for Aerobic Liquid phase Oxidation: Microreactors and Tube Reactors

The vitamin D₃ flow-chemical process is a good route for exercising circularity in chemistry; as the complex chemistry of this reaction limits the highest yield to only 25%, a recycling operation becomes mandatory. In this context, this research applies, for the first time, a circular economy assessment to a flow chemistry process, including reaction and separation. This is undertaken on the example of the photo-flow-chemical synthesis of vitamin D₃, previously developed by our group. In the research reported here, we develop a separation process to recycle the unreacted starting material 7-dehydrocholesterol after the photo-flow irradiation. We use acetonitrile for separation, instead of methanol, in the industrial process. In just one run, 90% of vitamin is extracted using dry acetonitrile as a separation solvent at 30 °C. A cumulative extraction efficiency of >99% is achieved after a second extraction step. The acetonitrile separation process connects directly to the subsequent vitamin crystallization using the same solvent. This eliminates the need to evaporate methanol in the industrial process; rather, the product is obtained just by cooling down. The Material Circular Indicator has been used as a central metric, and we needed to redefine this circularity metrics proposed by the Ellen MacArthur Foundation’s CE100 program to the world of flow chemistry. Rather than being able to take the parameter of lifetime and utility used in the original C100 definition, the frequency and dose of usage of medicinal products are taken here, both of which are connected to chemical productivity and waste generation. To explore the application of this adapted methodology to other pharmaceutical production processes, the results for the proposed vitamin D₃ flow-chemical process are compared with five processes for producing vitamins, painkillers, and an antibiotic. It is shown that the vitamin D₃ flow chemistry process with the new separation achieves a Material Circular Indicator of 0.94, a recycled fraction mass above 0.95, and an energy demand reduction by a factor of 2.

Volker Hessel

Papers

The Claisen Rearrangement – Part 2: Impact Factor Analysis of the Claisen Rearrangement, in Batch and in Flow

Microfluidic encapsulation for controlled release and its potential for nanofertilisers.

From Microreactor Design to Microreactor Process Design

Reactor Concepts for Aerobic Liquid phase Oxidation: Microreactors and Tube Reactors

Circular Economy Metrics for the Photo-High-p,T Continuous Multistep Synthesis of Vitamin D3